Many computer systems exclude potential users unnecessarily. Such exclusion often arises because of
a mismatch between designers’ perceptions of the wants and needs of the end-user and their actual
wants and needs. Sometimes the mismatch originates from the designer being unaware of the need to
design inclusively, or of methods for implementing inclusive design. Accessible user interfaces
make computers easily usable by people with disabilities involving physical or visual handicaps.

Our research has developed new techniques for characterising the interaction styles of a broad
range of users, and then investigated novel interaction techniques to suit individual users.

User modelling

We have developed a simulator to investigate how physical impairment affects human computer
interaction. This can predict possible interaction patterns when undertaking a task using a
variety of input devices, and estimate the time to complete a task in the presence of different
disabilities and for different levels of skill. The system complements existing methods of
usability evaluation, and should help designers to develop inclusive computer systems.

The simulator consists of three components:

The Application Model represents the tasks undertaken by users and decomposes them into atomic units.

The Interface Model considers the input and output devices to be used and represents their characteristics.

The User Model simulates the interaction patterns of users. This considers:

perception of visually impaired users by investigating their eye-gaze patterns

cognition of novices by using a dual-space model

motor-skill of motor-impaired users indicated by their grip strength and range of motion of different joints.

We have evaluated the predictive power of the simulator and demonstrated its use for selecting
between alternative designs and developing new techniques for interaction.